Relatives said that he was close to death, and that looters had “stolen all his medicine”. They insisted that they were being given no help from Gaddafi loyalists. Megrahi was pictured, clearly unconscious.

His son, Khaled al-Megrahi, told CNN: “We just give him oxygen. Nobody gives us any advice. There is no doctor. There is nobody to ask. We don’t have any phone line to call anybody. We just sit next to him … he has stopped eating and sometimes he goes into coma.”

Asked about the calls for his return to Britain, Megrahi’s son said: “If he is sent to Scotland, he will die, by the way. Here or there.”

The overthrow of Col Gaddafi, who paraded Megrahi as a victory over his western enemies, prompted calls by US senators for him to be sent back to Britain to complete his sentence.

But on Sunday night Mohammed al-Alagi, the National Transitional Council’s justice minister, dismissed suggestions that he may be extradited.

“We will not give any Libyan citizen to the West,” he said. “Al-Megrahi has already been judged once and he will not be judged again ... We do not hand over Libyan citizens.”

Charles Schumer and Kirsten Gillibrand, the senators for New York, home to many of the Lockerbie victims, last week called his release a “total miscarriage of justice” and demanded his extradition.

Megrahi was jailed for life in January 2001 for the bombing of Pan Am flight 103 from London to New York in December 1988. It killed all 259 on board and another 11 below in the Scottish town of Lockerbie .

Kenny MacAskill, the Scottish justice secretary, ruled in 2009 that Megrahi should be freed. His release came after Libyan leaders threatened to cancel lucrative oil and trade deals with Britain.

Gordon Brown and other British ministers insisted that they had not intervened and that the decision was one for the Scottish executive alone.

However documents released in February showed that ministers reversed their position on the transfer of Libyan prisoners in part due to commercial concerns, including after lobbying by the oil firm BP.

In an accompanying note, Sir Gus O’Donnell, the Cabinet Secretary, said that the British Government had come to the position that it “should do all it could” to ensure Megrahi’s release.

A secret US diplomatic cable obtained by WikiLeaks and published by The Daily Telegraph in January disclosed that British ministers sent Libya detailed legal advice on how to use Megrahi’s cancer diagnosis to push for his release from Scotland. David Cameron described the decision to release Megrahi as “profoundly wrong”.